GDI BitBlt() - no output

[watdg]

Hi. Below is a sample code that outputs a random graph unto a resizeable window. It will work find using a Win32 Project (VC++ 6.0). My goal is to add the BitBlt() function in order to reduce flicker (works like a double buffer that flips the graphics drawn at the back buffer memory to the front buffer). I know that it should be placed within WM_PAINT, but how and where? Can someone help me on this? Thanks.



#include <windows.h>
#include "time.h"
#include "stdio.h"

// TIMER VARIABLES
#define TIMER_ID1 1
#define TIMER_RATE1 500

// ENTRY VALUES
#define ENTRY_MAX 250
#define VALUE_MAX 750
#define VALUE_INTERVAL 15
#define VALUE_X 5
int n[ENTRY_MAX] = {0}; // INITIALIZED BEFORE MESSAGE LOOP

// WINDOW BOUNDARIES
#define MARGIN_LEFT 100
#define MARGIN_RIGHT 20
#define MARGIN_TOP 50
#define MARGIN_BOTTOM 50

// SET THE HORIZONTAL GAP
#define SPACE_X (rect.right-MARGIN_LEFT-MARGIN_RIGHT)/ENTRY_MAX

// GLOBAL RECTANGLE
RECT rect;

void Randomize();

LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
HINSTANCE g_hInst;
LPSTR lpszClass="Graph";


// ------------------------------------------------------------------------------------------
// WINDOWS REGISTRY
int APIENTRY WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance
,LPSTR lpszCmdParam,int nCmdShow)
{
HWND hWnd;
MSG Message;
WNDCLASS WndClass;
g_hInst=hInstance;

WndClass.cbClsExtra=0;
WndClass.cbWndExtra=0;
WndClass.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);
WndClass.hCursor=LoadCursor(NULL,IDC_ARROW);
WndClass.hIcon=LoadIcon(NULL,IDI_APPLICATION);
WndClass.hInstance=hInstance;
WndClass.lpfnWndProc=(WNDPROC)WndProc;
WndClass.lpszClassName=lpszClass;
WndClass.lpszMenuName=NULL;
WndClass.style=CS_HREDRAW | CS_VREDRAW;
RegisterClass(&WndClass);

hWnd=CreateWindow(lpszClass,lpszClass,WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,
NULL,(HMENU)NULL,hInstance,NULL);
ShowWindow(hWnd,nCmdShow);

// RANDOMIZE TIMER
srand(time(NULL));

// SET RANDOM VALUES
Randomize();

// SET THE TIMER
SetTimer(hWnd, TIMER_ID1, TIMER_RATE1, NULL);

while(GetMessage(&Message,0,0,0)) {
TranslateMessage(&Message);
DispatchMessage(&Message);
}
return Message.wParam;
}


// ------------------------------------------------------------------------------------------
// MESSAGE LOOP
LRESULT CALLBACK WndProc(HWND hWnd,UINT iMessage,WPARAM wParam,LPARAM lParam)
{
HDC hdc2;

PAINTSTRUCT ps;

HPEN Pen, OldPen;
HBRUSH Brush, OldBrush;
HFONT Font, OldFont;

LOGFONT lf;

switch(iMessage)
{
case WM_PAINT: {
hdc2=BeginPaint(hWnd,&ps);

// SET VIEW PORT
SetMapMode(hdc2,MM_ANISOTROPIC);
GetClientRect(hWnd,&rect);
SetWindowExtEx(hdc2,rect.right,rect.bottom,NULL);
SetViewportExtEx(hdc2,rect.right,rect.bottom,NULL);

// SET THE BRUSH COLOR
Brush = CreateSolidBrush(RGB(255,255,255));
OldBrush = (HBRUSH)SelectObject(hdc2,Brush);

// CLEAR THE RECT WITH SELECTED BRUSH
Rectangle(hdc2, 0,0,rect.right,rect.bottom);

// SET FONT AND OUTPUT VALUES
lf.lfWidth = 15;
lf.lfHeight = 15;
lf.lfEscapement = 0;
lf.lfOrientation = 0;
lf.lfWeight = 0;
lf.lfItalic = 0;
lf.lfUnderline = 0;
lf.lfStrikeOut = 0;
lf.lfCharSet = BALTIC_CHARSET;
lf.lfOutPrecision = 0;
lf.lfClipPrecision = 0;
lf.lfQuality = 0;
lf.lfPitchAndFamily = 0;

Font = CreateFontIndirect(&lf);
OldFont = (HFONT)SelectObject(hdc2,Font);

Pen=CreatePen(PS_SOLID, 1, RGB(255,0,0));
OldPen=(HPEN)SelectObject(hdc2, Pen);

char str[10];
double y=(double)rect.bottom-MARGIN_BOTTOM;

// OUTPUT VALUES AND HORIZONTAL GRID
for (int n=0; n<=VALUE_MAX; n+=VALUE_MAX/VALUE_INTERVAL) {
MoveToEx(hdc2,VALUE_X,y,NULL);
LineTo(hdc2,rect.right-MARGIN_RIGHT,y);
sprintf(str,"%d",n);
TextOut(hdc2,VALUE_X,y-(lf.lfHeight/2),str,strlen(str));
y-=(double)(rect.bottom-MARGIN_BOTTOM-MARGIN_TOP) /
VALUE_INTERVAL;
}

y = 0;

// DRAW VERTICAL LINES (DATA)
for (int i=0; i<ENTRY_MAX; i++) {
Pen=CreatePen(PS_SOLID, 1, RGB((255/VALUE_MAX)*n[i],
(255/VALUE_MAX)*n[i],(255/VALUE_MAX)*n[i]));
OldPen=(HPEN)SelectObject(hdc2, Pen);

MoveToEx(hdc2,(i*SPACE_X)+MARGIN_LEFT,rect.bottom-MARGIN_BOTTOM,
NULL);

y = ( (double)(rect.bottom-MARGIN_BOTTOM-MARGIN_TOP) /
VALUE_MAX ) * n[i];
y = (double)(rect.bottom-MARGIN_BOTTOM)-y;

LineTo(hdc2,(i*SPACE_X)+MARGIN_LEFT,y);
}

SelectObject(hdc2,OldPen);
DeleteObject(Pen);
SelectObject(hdc2,OldFont);
DeleteObject(Font);
SelectObject(hdc2,OldBrush);
DeleteObject(Brush);
DeleteObject(hdc2);

EndPaint(hWnd,&ps);
}
break;
case WM_TIMER: {
switch (wParam) {
case TIMER_ID1: {
Randomize();
InvalidateRect(hWnd, &rect, TRUE);
}
break;
}
}
break;
case WM_DESTROY: {
PostQuitMessage(0);
return 0;
}
}
return(DefWindowProc(hWnd,iMessage,wParam,lParam));
}


// SET RANDOM VALUES
void Randomize()
{
for (int i=0; i<ENTRY_MAX; i++)
n[i] = rand()%(VALUE_MAX);
}

[watdg]

You know what? I don't think there's a solution for this one. I'll just have to use DirectX for this although this program doesn't need further modification. It's good as it is. Unless, I'm designing a fast-paced game, the flickering shall be tolerated.

:WAVE: